The present invention relates generally to systems that output a liquid at a user-defined constant temperature and more particularly to a tank for use in a system that outputs a liquid at a user-defined constant temperature, the tank being designed to receive and store a supply of the liquid which is in turn used by the system to control the temperature of a piece of equipment.
Systems that output a liquid, such as water, at a user-defined constant temperature to regulate the temperature of a piece of equipment, such as a welding machine, laser or molding machine, are well known in the art.
Systems of the type as described above which are used primarily to cool down the temperature of a piece of equipment as opposed to heat up the temperature of the piece of equipment are commonly referred to in the art as chillers. An example of a chiller may be found in U.S. Pat. No. 4,802,338 to P. D. Oswalt etc.
Referring now to FIG. 1, there is shown a simplified block diagram of a conventional chiller 11 which is connected to a particular piece of equipment 13 by a continuous fluid path 15 through which coolant circulates in one direction. As will be described in detail below, chiller 11 is responsible for both reducing the temperature of the coolant and in turn pumping the low temperature coolant through the piece of equipment 13. Based on well-known thermal exchange principles, the low-temperature coolant provided by chiller 11 thus serves to reduce the temperature of piece of equipment 13. However, as a result of the thermal exchange process, the temperature of the coolant rises as it passes through piece of equipment 13. Accordingly, the higher temperature coolant is directed by fluid path 15 back into chiller 11 where it is subsequently reduced in temperature and thereby available for re-circulation through device 13. In this manner, a continuous coolant cycle is established between chiller 11 and device 13.
As can be seen, chiller 11 is provided with a refrigeration system 17 for reducing the temperature of the supply of coolant which returns to chiller 11 from device 13. Chiller 11 additionally includes a tank 19 which serves as a means for (i) receiving and storing coolant, (ii) collecting the return supply of coolant which has been reduced in temperature by refrigeration system 17 and (iii) introducing additional coolant into fluid path 15 as deemed necessary (e.g., as a result of coolant evaporation). Furthermore, chiller 11 includes a pump 21 which is responsible for drawing a supply of chilled coolant from tank 19 and in turn for circulating said coolant through fluid path 15 (i.e., delivering said chilled coolant to device 13). In some chillers 11, a portion of the liquid from pump 21 is not sent to piece of equipment 13, but rather is sent back to tank 19 after it passes through a deionizer 22. A temperature sensor 23 is preferably provided in chiller 11 at a point along fluid path 15 as the chilled coolant exits chiller 11 for coolant temperature monitoring purposes.
As noted above, refrigeration system 19 serves to reduce the temperature of the supply of coolant which returns to chiller 11 from device 13. Refrigeration system 19 includes a compressor 25, a condenser 27, an expansion device 29 and a heat exchanger 31 that are interconnected by a continuous refrigerant fluid path 33 through which a supply of refrigerant circulates in one direction. In use, compressor 25 draws low pressure, low temperature refrigerant gas (e.g., gas having a temperature of approximately 60° F. and a pressure of approximately 35 psi) through a suction line and compresses the gas so as to yield a high pressure, high temperature refrigerant gas (e.g., gas having a temperature of approximately 170° F. and a pressure of approximately 120 psi). Condenser 27 cools and liquefies the high pressure, high refrigerant gas without modifying its pressure so as to yield a high pressure liquid refrigerant (e.g., liquid having a temperature of 100° F. and a pressure of approximately 120 psi). Expansion device 29 expands the high pressure liquid refrigerant so as to yield a low pressure, low temperature, primarily liquid-based refrigerant (e.g., liquid having a temperature of approximately 30° F. and a pressure of approximately 35 psi).
As can be seen in FIG. 1, both coolant fluid path 15 and refrigerant fluid path 33 pass through heat exchanger 31. Accordingly, the low temperature liquid refrigerant which passes through fluid path 33 reduces the temperature of the coolant circulating through fluid path 15. However, the above-described thermal transfer causes the low temperature liquid refrigerant in fluid path 33 to evaporate in heat exchanger 31. The evaporated refrigerant is discharged from heat exchanger 31 as a low pressure gaseous refrigerant which, in turn, is drawn into the suction line of compressor 25, thereby creating a continuous refrigerant cycle.
Traditionally, a tank for use in a system that outputs a liquid at a user-defined constant temperature (e.g., chiller tank 19 in prior art FIG. 1) includes a plurality of input ports through which the liquid is introduced into the tank and a single discharge port through which liquid is discharged from the tank, all of said ports being separate from one another and in fluid communication with the chamber inside the tank.
Commonly, the thermally controllable liquid is input into the tank through one or more of the following input ports, namely: (1) a return port which is designed to receive the liquid that has already been used to regulate the temperature of the particular piece of equipment (e.g., the re-circulated coolant reduced in temperature by heat exchanger 31 in FIG. 1); (2) a manual fill port which is designed to receive new, unused liquid by manual means (e.g., through a pouring process); and (3) an auxiliary port which is designed to receive new, unused liquid from a source by automated means or return liquid emitted by pump 21 but which has not passed through piece of equipment 13.
It should be noted that a system that outputs a liquid at a user-defined constant temperature and includes a tank for receiving and storing liquid is also often provided with one or more of the following optional devices in addition to the deionizer noted above which is disposed outside of the tank for deionizing the liquid contained therein; (1) a heater extending into the tank for heating the liquid contained therein (i.e., when the system requires the temperature of liquid to be raised); (2) an immersion pump extending into the tank for withdrawing liquid contained therein (i.e., as a replacement for external pump 21); (3) two or more filters disposed inside the tank at either the fill port, the discharge port or the return port and (4) a sight gauge coupled to the tank through fittings for providing a visual indication of the level of thermally controllable liquid contained therein.
Although well known and widely used in the art, tanks of the type described above have been found to experience at least some of the following shortcomings.
As a first shortcoming, as noted above, tanks of the type as described above typically mount the deionizer outside of the tank, the deionizer being coupled to the tank by means of one or more hoses or pipes. Although functionally satisfactory, this arrangement substantially increases the overall dimensions of the system, which is highly undesirable.
As a second shortcoming, tanks of the type described above are not universally constructed to receive any one of either a deionizer, or a heater or an immersion pump. Rather, a unique tank is typically constructed for use in conjunction with each of the above-identified devices, thereby increasing manufacturing costs (i.e. to fabricate three differently constructed tanks), which is highly undesirable.
As a third shortcoming, tanks of the type described above are not typically provided with filtration means at the return port. As a result, liquid introduced through the return port may introduce unwanted particles of material into the interior of the tank. As a result, certain devices that maybe disposed inside the tank (e.g., a heater, immersion pump, etc.) may be exposed to the unwanted particles of material, which is highly undesirable.
As a fourth shortcoming, tanks of the type described above typically mount a sight gauge (also commonly referred to as a sight tube) on the outer surface of the tank housing, wherein the sight gauge is coupled to the interior of the tank through fittings provided in a wall of the tank and on the sight gauge itself. As can be appreciated, it has been found that these fittings represent potential leak points, which is highly undesirable.
As a fifth shortcoming, all of the various components for a system that outputs a liquid at a user-defined constant temperature are typically mounted within an outer protective shell (i.e. system housing) so as to render the system compact and unitary in nature, the outer shell often including a plurality of metal or plastic panels secured together in a box-type configuration. In most conventional systems, the manual fill port of the tank protrudes up through a small circular opening provided in one panel of the outer protective shell (e.g., the top panel). Because this construction renders the interior chamber externally accessible through manual fill port (and thereby susceptible to contaminants), it is to be understood that the manual fill port is typically sealed off with a cap which can be easily removed when needed in order to pour fluid into the chamber. The above-described design introduces two notable disadvantages: (1) the particular shape of the manual fill port is not conducive to pouring liquid therethrough without substantial splashing, and (2) a small annular space is created between the manual fill port of the tank and the panel of the outer protective shell, said space serving as a means by which moisture (e.g., splashed coolant) may enter into the system and potentially damage selected components contained therein. As a result, an enlarged removable funnel is often inserted into the manual fill port during the liquid pouring process. However, as can be appreciated, the use of a removable funnel in this manner has been found to be not entirely satisfactory.